TM 5-3805-258-24-1H Y D R A U L I C S Y S T E MS Y S T E M S O P E R A T I O NFLOAT PositionLIFT AND TILT PILOT VALVE(Lower Stem In FLOAT Position)12. Lower stem. 14. Holes. 16. Vent passage. 17. Tankpaseage. 18. Paaaage to lift valveepool. 20. Pump (sup-ply)pasaage. 23. Groove.When the lift control lever is moved to FLOATposition, there is a detent that holds the lever inFLOAT. The movement in the lift and tilt pilot valveis the same as in LOWER position, except lower stem(12) is pushed down farther. Vent passage (16) isnow open to tank passage (17) through groove (23).The oil in vent passage (16) holds the make-up valve,for the rod end of the lift cylinders, closed inLOWER position. In FLOAT position, the make-upvalve opens and lets oil from the implement pumpsection go directly to drain (tank). There is no pres-sure oil to the rod end of the lift cylinders, so theweight of the bucket and lift arms causes the bucketto lower.The flow of oil from pump passage (20) throughholes (14) and out passage (18) is the same as inLOWER position. The lift valve spool is in the sameposition in LOWER and FLOAT.LOWER Position With Engine OffThe bucket can be lowered with the engine off.The oil supply comes from the head end of the liftcylinders into pump passage (20). When the lift con-trol lever is moved to LOWER position and on toFLOAT position, the bucket will lower to theground.The operation of lower stem (12) is the same as inFLOAT position when the engine is running. Ventpassage (16) is again opened to tank passage (17)which vents (releases pressure oil) the make-upvalve for the rod end of the lift cylinders. Oil fromthe tank will now go around the lift valve spool tothe rod end of the lift cylinders. The weight of thebucket and lift arms causes the bucket to lower.NOTE: When the engine is off and the lift arms areraised, the bucket can also be dumped.HOLD Position Of Tilt OperationWhen the tilt control lever is in HOLD position,plungers (26) and (27) are in the same position (asshown). The plungers do not push up against actua-tor (24) in the hold position. Pressure oil from thepilot pump section goes through pump passage (20)and is stopped by the position of stems (34) and (35).Holes (36) and (37) are open to tank passage (11).Spring (33) pushes up on retainer (28) andplunger (26). Spring (31) holds dump stem (35)down against retainer (28). Spring (32) pushes uponretainer (29) and plunger (27). Spring (30) holds tiltback stem (34) down against retainer (29). There arespacers between the retainers and plungers that areused to change the force of springs (30) and (31).TILT BACK PositionWhen the tilt control lever is moved to TILTBACK position, the control lever turns shaft (25)and actuator (24) in a clockwise direction. The move-ment of the plunger and stem in the pilot valve is thesame as in RAISE position. Tilt back stem (34)moves down and oil from pump passage (20) goesthrough holes (36). The oil goes out passage (22) toone end of the tilt valve spool. The tilt valve spoolmoves into TILT BACK position.The oil from the chamber at the opposite end of thetilt valve spool comes back through passage (21).This oil goes through holes (37) of dump stem (35)into tank passage (11).3-98